The Caldwell Objects

70 & 72
A T THIS POINT I ' VE CHOSEN TO BREAK THE
numerical order of the Caldwell Catalog to discuss
two objects that are close to one another on
the sky. The late-type spiral galaxies NGC 300
(Caldwell 70) and NGC 55 (Caldwell 72) are
members of the Sculptor Group of galaxies,
which includes NGC 247 (Caldwell 62) and NGC
253 (Caldwell 65). They lie roughly along the
same parallel (that is, at nearly equal
declinations) and are separated by 8°. NGC 300 is
the more northerly of the pair (by 1½°) and the
more easterly (by 77 /8°). Although both galaxies
belong to Sculptor, they lie near the
constellation's southern border, just "across the
tracks" from Phoenix. In fact, they are best found
by using magnitude-2.4 Alpha (α) Phoenicis
(Ankaa) as a guide. NGC 55 lies 3¾° northwest of
Ankaa, at the end of a zigzagging chain of
binocular stars. NGC 300 lies 7¼° northeast of
Ankaa in a more desolate patch of sky. Finding it
is a cinch from dark southerly observing sites,
though, because it is 1¾° northwest of 5.6magnitude
Xi (ξ) Sculptoris. But from north
temperate latitudes it's best to star-hop from
bright Ankaa. Begin by moving your telescope
1¾° north-northeast from Ankaa to a pair of 7thmagnitude
suns. Another 1¼° to the northnortheast
lies an acute triangle of 8th- and 9thmagnitude
stars, which is just 1° east of a 5thmagnitude
sun. A longer sweep of about 2° to the
northeast brings us to a pair of 6th-mag-nitude
stars, Lambda1,2 (λ1,2 ) Sculptoris. NGC 300 is yet
another 2° to the east-northeast of Lambda2 Sculptoris, the eastern member of that pair.
In 1834 John Herschel took credit for discovering
NGC 300 at the Cape of Good Hope
with his 18¼-inch reflector. However, James
Dunlop listed the object in A Catalogue of Nebulae
and Clusters of Stars in the Southern
Hemisphere, Observed at Parramatta in New South
Wales, which was published in 1827. Dunlop
discovered NGC 300 while surveying the
southern skies from Australia with a 9-inch f/12
reflector. John Herschel did acknowledge that the
object he found was the 530th in Dunlop's
catalog, of which Dunlop had written, a "pretty
large faint nebula, irregular round figure 6' or 7'
diameter, easily resolvable into exceedingly
minute stars, with four or five
stars of more considerable magnitude; slight
compression of the stars to the centre." But
during his stay in Africa, the junior Herschel
became dissatisfied with Dunlop's survey; he
found himself unable to reidentify about twothirds
of the objects in it. In the case of Dunlop
530 Herschel wrote: "Mr. Dunlop's neb 530 is
described by him as easily resolvable into very
minute stars. Its identity with [NGC 300] is
therefore very doubtful."
But i it doubtful? s The Herschels and many
of their contemporaries had imagined that they
had resolved many nebulae into stars when there
really weren't any stars to resolve. So why
278 Deep-Sky Companions: The Caldwell Objects